In UMTS (Universal Mobile Telecommunications System) networks, for the purpose of improving spectral efficiency and further improving data rates, by adopting HSDPA (High Speed Downlink Packet Access) and HSUPA (High Speed Uplink Packet Access), it is performed exploiting maximum features of the system based on W-CDMA (Wideband Code Division Multiple Access). For the UMTS network, for the purpose of further increasing high-speed data rates, providing low delay and the like, Long Term Evolution (LTE) has been studied.
In the 3G system, a fixed band of 5 MHz is substantially used, and it is possible to achieve transmission rates of approximately maximum 2 Mbps in downlink. Meanwhile, in the LTE-scheme system, using variable bands ranging from 1.4 MHz to 20 MHz, it is possible to achieve transmission rates of maximum 300 Mbps in downlink and about 75 Mbps in uplink. Further, in the UMTS network, for the purpose of further increasing the wide-band and high speed, successor systems to LTE have been studied (for example, LTE Advanced (LTE-A)). For example, in LTE-A, it is scheduled to increase 20 MHz that is the maximum system band in LTE specifications to about 100 MHz.
In the LTE-scheme system (LTE system), MIMO (Multi Input Multi Output) systems are proposed as radio communication techniques for transmitting and receiving data using a plurality of antennas and improving a data rate (spectral efficiency) (for example, see Non-patent Document 1). In the MIMO systems, the transmitter/receiver is provided with a plurality of transmission/reception antennas, and the transmitter (for example, base station apparatus eNB) simultaneously transmits different transmission information sequences from different transmission antennas. Meanwhile, the receiver (for example, mobile station apparatus UE) side exploits the fact that different fading variations occur between transmission and reception antennas, and divides the simultaneously-transmitted information sequences to detect, and it is thereby possible to increase the data rate (spectral efficiency). In addition, in the LTE system are specified Single User MIMO (SU-MIMO) transmission in which transmission information sequences simultaneously transmitted from different transmission antennas are all for the same user and Multiple User MIMO (MU-MIMO) transmission in which the transmission information sequences are for different users.
Further, in the LTE-A-scheme system (LTE-A system), transmission and reception of data channel signals by Coordinated Multiple Point (CoMP) is studied, for the purpose of reducing inter-cell interference or improving the reception signal intensity. By performing transmission and reception by the CoMP, particularly, it is expected to improve system characteristics in a mobile station apparatus UE positioned at the cell edge. Base station apparatuses eNBs of a plurality of cells generate precoding weights of data channel signals for each mobile station apparatus UE, based on a measurement value of CSI (Channel State Information) transmitted from each mobile station apparatus UE as feedback. As a transmission method by CoMP, for example, Joint Transmission (JT) is proposed in which base station apparatuses eNBs of a plurality of cells join data channel signals (PDSCH: Physical Downlink Shared Channel) to the same mobile station apparatus UE to transmit.